title: The azygos defibrillator lead for elevated defibrillation thresholds: implant technique, lead stability, and patient series.
abstract: BACKGROUND
  Conventional insertion of implantable cardioverter-defibrillator (ICD) includes an evaluation of the defibrillation threshold (DFT). Implanting an ancillary defibrillation lead in the azygos vein has been introduced as a therapeutic option in patients with "high" DFT. This study reports the efficacy and stability of azygos defibrillation coils implanted for elevated DFTs.
  
  
  METHODS
  This is a retrospective review of seven consecutive patients with right and left pectoral, single- and dual-chamber, and biventricular ICDs and elevated DFTs, in whom an azygos defibrillation coil was introduced.
  
  
  RESULTS
  Addition of an azygos defibrillator lead achieved a satisfactory safety margin during single energy defibrillation efficacy testing in four out of seven patients, with success at maximum device output in two patients. No satisfactory safety margin was achieved in the remaining patient, despite the further addition of a subcutaneous defibrillation coil. No change in lead position was observed over a mean radiographic follow-up of 8 months. No complications were noted during a mean follow-up of 14 months, including no deaths, and no ICD shocks.
  
  
  CONCLUSIONS
  Implanting a defibrillation coil into the azygos vein is feasible and safe. In a majority of patients with failed defibrillation efficacy testing, adding an azygos coil achieves success on repeat testing. Therefore, this technique is one option for lowering the defibrillation threshold in patients who fail DFT testing of their ICD.
authors.affiliation: Washington University School of Medicine, St Louis, Missouri 63110, USA.
authors.forename: Jonas A
authors.initials: JA
authors.lastname: Cooper
authors.forename: Matthew P
authors.initials: MP
authors.lastname: Latacha
authors.forename: Gabriel E
authors.initials: GE
authors.lastname: Soto
authors.forename: Richard G
authors.initials: RG
authors.lastname: Garmany
authors.forename: Marye J
authors.initials: MJ
authors.lastname: Gleva
authors.forename: Jane
authors.initials: J
authors.lastname: Chen
authors.forename: Mitchell N
authors.initials: MN
authors.lastname: Faddis
authors.forename: Timothy W
authors.initials: TW
authors.lastname: Smith
mesh_terms: D000293:Adolescent; D000328:Adult; D001401:Azygos Vein / Q000601:surgery*; D017147:Defibrillators, Implantable; D004567:Electrodes, Implanted; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005260:Female; D006333:Heart Failure / Q000175:diagnosis / Q000517:prevention & control*; D006801:Humans; D008297:Male; D008875:Middle Aged; D019919:Prosthesis Implantation / Q000379:methods*; D012189:Retrospective Studies; D016896:Treatment Outcome; D055815:Young Adult